A known swimming flipper is a device worn on the feet to increase the thrust of leg movement in swimming; with the swimming flipper swimmers can swim comparatively easily and for a longer time. There are various kinds of flippers available on the market, but the known flippers are of such a design that the fin of a flipper is integrated with and extended from the sole of the shoe (see FIG. 1), thus the above mentioned conventional flippers have some disadvantages. Firstly, with the conventional flippers, the force is exerted by a wearer's tiptoes which results in a low efficiency of the swimming flipper and sometimes causes swimmers to be seized with cramp of the calf muscles (a painful tightening of the calf muscles). When this is serious, the swimmers must be helped out of water by life-guards or by the aid of life preservers. Secondly, due to the fact that, with the conventional flipper, the efficiency is rather low and the function of the flipper cannot be brought into full play.
Therefore it is highly desirable to have a flipper of new design which can overcome the above mentioned disadvantages, namely to improve the efficiency of the flippers so as to save more effort while swimming, to allow flipper wearers to use reasonably the force-exerting portion of the feet while swimming so as to last for a longer time while avoiding painful cramp of the calf muscles.